Chemical mechanical polishing with a small polishing pad

Abstract

A chemical mechanical polishing apparatus includes a rotating plate on which a substrate is received, and a polishing pad which moves across the substrate as it rotates on the plate to polish the substrate. The load of the pad against the substrate, and the rotary speed of the plate, may be varied to control the rate of material removed by the pad.

What is claimed is: 
     
       1. A method of chemical mechanical polishing a substrate, comprising: locating a substrate on a member, the substrate having a planar surface suitable for integrated circuit fabrication;   rotating the member to rotate the substrate;   positioning a polishing pad that is smaller than the substrate on the surface of the substrate as the substrate rotates;   rotating the polishing pad with a motor;   applying a load to force the polishing pad against the substrate with a load member located between the motor and the polishing pad;   supplying a chemically reactive liquid to the polishing pad; and   moving the polishing pad laterally parallel and linearly across the rotating surface of the substrate between an edge and a center of the substrate to polish the substrate.   
     
     
       2. The method of claim 1, further comprising biasing the polishing pad against the rotating surface of the substrate as the substrate rotates. 
     
     
       3. The method of claim 2, further comprising varying the bias force of the polishing pad against the rotating surface of the substrate as the polishing pad moves across the rotating surface. 
     
     
       4. The method of claim 3, further comprising varying the speed of rotation of the substrate as the polishing pad moves across the rotating surface of the substrate. 
     
     
       5. The method of claim 1, further comprising cleaning the polishing pad before the positioning step. 
     
     
       6. The method of claim 1, wherein the surface area of the polishing pad which contacts the substrate is at least ten times smaller than the surface area of the substrate. 
     
     
       7. The method of claim 1, wherein the polishing pad is connected to a lower end of a polishing arm, and wherein rotating the polishing pad includes rotating the polishing arm. 
     
     
       8. The method of claim 7, wherein moving the polishing pad includes moving the polishing arm laterally parallel to the surface of the substrate. 
     
     
       9. An apparatus of chemical mechanical polishing a substrate, comprising: a rotatable member for receiving and rotating a substrate having a planar surface suitable for integrated circuit fabrication;   a rotatable polishing arm connected to the polishing pad to rotate the polishing pad and to move the polishing pad laterally to and linearly across a rotating surface of the substrate between and edge and a center of the substrate to polish the substrate, the polishing pad being smaller than the substrate;   a motor to rotate a drive shaft;   a load member connecting the polishing arm to the drive shaft; and   a slurry supply to provide selectively a chemically reactive liquid to the polishing pad.   
     
     
       10. The apparatus of claim 9, wherein the load member is a variable load member. 
     
     
       11. The apparatus of claim 10, wherein the motor is a variable speed motor. 
     
     
       12. The apparatus of claim 11, further comprising a process controller interconnected to, and controlling, said variable load member and said variable speed motor. 
     
     
       13. The apparatus of claim 9, wherein the surface area of the polishing pad in contact with the rotating upper surface of the substrate is at least ten times smaller than the surface area of the substrate. 
     
     
       14. The apparatus of claim 9, wherein the polishing pad is connected to a lower end of the polishing arm and is selectively engageable with the substrate. 
     
     
       15. The apparatus of claim 9, wherein the polishing pad is connected to a lower end of the polishing arm and is selectively engageable with the substrate.